Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/07—Preparation of halogenated hydrocarbons by addition of hydrogen halides
  • C07C17/08—Preparation of halogenated hydrocarbons by addition of hydrogen halides to unsaturated hydrocarbons

Definitions

• the present invention relates to a continuous process for the preparation of cyclopentyl bromide by reacting cyclopentene with hydrogen bromide
• Cyclopentyl bromide is mainly used as an alkylating reagent to transfer the cyclopentyl radical.
• pharmaceuticals and agrochemicals are manufactured in this way.
• EP-A 1 414 019 describes lipoxygenase inhibitors and EP-A 1 635 485 herbicides, the production of which uses cyclopentyl bromide.
• cyclopentanol can be converted into cyclopentyl bromide by reaction with phosphorus tribromide.
• cyclopentane or cyclopentene include: The reaction of cyclopentane with methylene bromide and antimony pentafluoride (J. Org. Chem. 54 , 1643 (1989)) and the hydroboration of cyclopentene and cleavage of the intermediate tricyclopentylborane with bromine (Tetrahedron 40 , 2763 to 2784 (1988)).
• the object was therefore to find an economical process for the preparation of cyclopentyl bromide.
• the starting materials can be pure or diluted and passed over the catalyst in a condensed, partially condensed or gaseous state.
• the reaction products can be used, especially when working in the gas phase, e.g. by condensation from the product stream.
• cyclopentene is used together with an inert gas stream, e.g. with nitrogen, carbon dioxide or argon, and with the addition of hydrogen bromide and a recycled portion of cyclopentene in vapor form into the reaction zone.
• an inert gas stream e.g. with nitrogen, carbon dioxide or argon
• cyclopentene is used, optionally in the presence of a reaction mixture stable diluent, in condensed form, for example in the form of a trickle phase reaction, reacted with hydrogen bromide, it being possible for the hydrogen bromide to be metered in cocurrently or countercurrently to cyclopentene.
• the reaction of cyclopentene with hydrogen bromide according to the invention can e.g. at temperatures between -20 and + 300 ° C, preferably between 0 and 150 ° C and particularly preferably between 10 and 110 ° C and e.g. at pressures between 0.01 and 30 bar, preferably between 0.1 and 10 bar, particularly preferably between 0.5 and 5 bar and particularly preferably between 0.8 and 1.5 bar.
• Suitable heterogeneous catalysts for the process according to the invention are e.g. Metal compounds that are applied to carrier materials. It is also possible to use lumpy, shaped or unshaped solids which can be obtained after mixing metal compounds with base materials for support materials and subsequent mechanical treatment or shaping. Such manufacturing processes are generally known to the person skilled in the art.
• metal compounds are metal salts, e.g. those of copper, iron, cobalt, nickel, chromium, bismuth, zinc, cadmium, vanadium, tungsten, mercury, antimony, aluminum and / or molybdenum.
• the salts of inorganic acids such as fluorides, chlorides, bromides, sulfates and / or phosphates of the metals mentioned are preferred.
• metal salts derived from organic acids can also be used to prepare the catalysts according to the invention. Such catalysts generally convert to the corresponding bromides under the reaction conditions.
• Suitable carrier materials are activated carbon, silica gel, silicon dioxide, silicas, aluminum oxide, oxides and phosphates of rare earth metals, zeolites, aluminosilicates, solid heteropolyacids such as niobium heteropolyacids and ceramic bodies.
• cyclopentene Based on 1 mol of cyclopentene, for example 0.05 to 5 mol of hydrogen bromide can be used. This amount is preferably 0.1 to 2 mol.
• the reaction mixture present after the reaction according to the invention can be worked up, for example, as follows: If work was carried out at higher temperatures, the portions which can be condensed, for example, at 0 ° C. or lower temperatures are first condensed. The condensate obtained in this way can then be separated, for example by distillation. Cyclopentyl bromide is thus generally obtained with conversions of over 45% and in selectivities of over 80%. Unreacted cyclopentene present in the reaction mixture can also be separated off in this way (it then generally remains in the gas phase) and returned to the process. Any unreacted hydrogen bromide present in the reaction mixture can be removed before or after the condensation by washing, for example with water.
• the process according to the invention can be carried out, for example, with a catalyst load (GHSV) of 100 to 10,000 h -1 , preferably 200 to 5,000 h -1 .
• GHSV catalyst load
• the reaction mixture is preferably worked up by feeding the reaction mixture leaving the reactor, for example a tube bundle reactor, to a separating device in which cyclopentyl bromide is separated off.
• the separation device can be, for example, a distillation column in which cyclopentyl bromide is removed as the bottom product.
• the gas phase obtained at the top of the column can be fed to a condenser.
• the condensate obtained there can be partly returned as reflux to the upper part of the distillation column and partly returned to the reactor.
• the gas phase leaving the condenser is returned to the reactor, with can discharge a small part of it and thus remove by-products from the process.
• the procedure is as follows: the reactor is operated at temperatures in the range from 20 to 100 ° C. and at pressures in the range from 0.5 to 5 bar.
• a mixture is fed to it which contains, for example, 5 to 15% by weight of cyclopentene, 60 to 90% by weight of inert gas, 2 to 10% by weight of hydrogen bromide, 0 to 10% by weight of cyclopentyl bromide and 0 to 10% by weight.
• % contains low-boiling by-products recycled together with cyclopentene.
• the reaction mixture leaving the reactor is fed to a distillation column which is operated in such a way that a gaseous top product with temperatures in the range from 0 to 100 ° C.
• cyclopentene 65 to 95 wt .-% inert gas, 0 to 5 wt .-% hydrogen bromide, 5 to 20 wt .-% cyclopentyl bromide and 0 to 10 wt .-% volatile by-products, and at temperatures in the range 50 to 200 ° C a liquid bottom product containing at least 95 wt .-% cyclopentyl bromide.
• the gaseous top product is cooled to give a condensate with a temperature of -50 to + 50 ° C, the 1 to 80 wt .-% cyclopentene, 10 to 95 wt .-% cyclopentyl bromide, 0 to 5 wt .-% hydrogen bromide and Contains 0 to 50 wt .-% by-products.
• This condensate is divided in a ratio of 10: 1 to 1:10 into two partial streams, one of which is returned to the upper part of the distillation column as reflux and the other is returned to the reaction.
• the gas phase remaining after the top product of the distillation column has cooled contains 75 to 95% by weight of inert gas, 0 to 15% by weight of cyclopentene, 0 to 5% by weight of hydrogen bromide, 0 to 15% by weight of cyclopentyl bromide and 0 to 10 Wt% by-products.
• a proportion of 0.5 to 10% by weight is discharged from this gas phase, the rest is returned to the reaction.
• the process according to the invention has the advantages that it starts from simple, inexpensive and readily accessible starting materials, delivers cyclopentyl bromide in good yields and selectivities, no particular ecological expenditure is necessary and little useless by-products (for example polymers) are obtained. It can also be carried out continuously with good results and high economic efficiency.
• a nitrogen stream of 5 Nl / h was passed continuously through a gas washing bottle containing cyclopentene, and the gas stream thus saturated with cyclopentene was passed over the catalyst at 40 ° C. after the continuous addition of gaseous hydrogen bromide (4 g / h).
• the reaction product obtained at the outlet of the glass tube was condensed by cooling to -10 ° C.
• a sample of the condensate was washed with dilute sodium hydrogen carbonate solution and analyzed by gas chromatography.
• the conversion based on the cyclopentene used was 50%, the selectivity based on the cyclopentene used was 90%.
• the catalyst and the reaction vessel were as in Example 1.
• Liquid cyclopentene (12 g / h) and gaseous hydrogen bromide (4 g / h) were fed continuously into the glass tube by means of a pump.
• the temperature of the catalyst was 50 ° C.
• Example 1 In a tube bundle reactor (dimensions: length 3000 mm and diameter: 300 mm) containing 109 individual tubes, each with a diameter of 37 mm and a wall thickness of 6.5 mm, 350 l of a catalyst prepared as in Example 1 were introduced. A cooling liquid kept at 30 ° C. flowed through the jacket space of the reactor.
• the gas stream leaving the reactor had a temperature of 40 ° C. and was introduced into a column (length: 3300 mm, diameter: 300 mm). At the top of the column there was a heat exchanger which was regulated by cooling with brine so that the gas emerging behind the condenser and the liquid flowing out of the condenser each had a temperature of -10 ° C.
• the gas leaving the condenser contained 4.7% by weight of cyclopentene, 0.7% by weight of hydrogen bromide, 1.0% by weight of cyclopentyl bromide, 91.7% by weight of nitrogen and 2.0% by weight of cyclopentane and the liquid draining from the condenser 10.6% by weight of cyclopentene, 83.7% by weight of cyclopentyl bromide and 5.6% by weight of cyclopentane.
• the gas was heated to a temperature of 25 ° C. and 0.65% by weight (1.7 kg / h) of it was continuously discharged and disposed of. The remaining gas stream was returned to the reaction.
• the bottom stream (30 kg / h) leaving the column had a temperature of 130 ° C. and contained 99% by weight of cyclopentyl bromide.
• the liquid running out of the condenser was divided into two substreams, one of which was returned to the upper region of the column and the other to the reaction.
• the weight ratio of the partial streams mentioned was 6: 1 (reflux into the column: recycle into the reaction).
• the cyclopentyl bromide reaction product thus obtained was suitable for further reactions, for example alkylations, without further purification.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)
• Catalysts (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 1996
  • 1996-07-01 EP EP96110592A patent/EP0753499B1/fr not_active Expired - Lifetime
  • 1996-07-01 DE DE59607066T patent/DE59607066D1/de not_active Expired - Fee Related
  • 1996-07-01 AT AT96110592T patent/ATE202067T1/de not_active IP Right Cessation
  • 1996-07-01 ES ES96110592T patent/ES2157371T3/es not_active Expired - Lifetime
  • 1996-07-04 JP JP8192699A patent/JPH0925251A/ja active Pending
  • 1996-07-05 US US08/676,027 patent/US5744663A/en not_active Expired - Lifetime
  • 1996-07-09 CA CA002180814A patent/CA2180814A1/fr not_active Abandoned

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Non-Patent Citations (7)

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